Procedure for etch rate consistency

ABSTRACT

Methods of conditioning interior processing chamber walls of an etch chamber are described. A fluorine-containing precursor may be remotely or locally excited in a plasma to treat the interior chamber walls periodically on a preventative maintenance schedule. The treated walls promote an even etch rate when used to perform gas-phase etching of silicon regions following conditioning. Alternatively, a hydrogen-containing precursor may be remotely or locally excited in a plasma to treat the interior chamber walls in embodiments. Regions of exposed silicon may then be etched with more reproducible etch rates from wafer-to-wafer. The silicon etch may be performed using plasma effluents formed from a remotely excited fluorine-containing precursor.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Prov. Pat. App. No.61/910,830 by Zhang et al., filed Dec. 2, 2013, and titled “PROCEDUREFOR ETCH RATE CONSISTENCY,” which is hereby incorporated herein byreference and in its entirety for all purposes.

FIELD

Embodiments of the invention relate to conditioning a substrateprocessing region.

BACKGROUND

Integrated circuits are made possible by processes which produceintricately patterned material layers on substrate surfaces. Producingpatterned material on a substrate requires controlled methods forremoval of exposed material. Chemical etching is used for a variety ofpurposes including transferring a pattern in photoresist into underlyinglayers, thinning layers or thinning lateral dimensions of featuresalready present on the surface. Often it is desirable to have an etchprocess which etches one material faster than another helping e.g. apattern transfer process proceed. Such an etch process is said to beselective of the first material. As a result of the diversity ofmaterials, circuits and processes, etch processes have been developedthat selectively remove one or more of a broad range of materials.However, there are few options for selectively etching silicon using gasphase reactants.

Dry etch processes are often desirable for selectively removing materialfrom semiconductor substrates. The desirability stems from the abilityto gently remove material from miniature structures with minimalphysical disturbance. Dry etch processes also allow the etch rate to beabruptly stopped by removing the gas phase reagents. Some dry-etchprocesses involve the exposure of a substrate to remote plasmaby-products formed from one or more precursors. For example, remoteplasma generation of nitrogen trifluoride in combination with ionsuppression techniques enables silicon to be selectively removed from apatterned substrate when the plasma effluents are flowed into thesubstrate processing region. However, process improvements are needed toimprove the utility of these remote plasma processes.

Methods are needed to maintain consistent silicon etch rates.

SUMMARY

Methods of conditioning interior processing chamber walls of an etchchamber are described. A fluorine-containing precursor may be remotelyor locally excited in a plasma to treat the interior chamber wallsperiodically on a preventative maintenance schedule. The treated wallspromote an even etch rate when used to perform gas-phase etching ofsilicon regions following conditioning. Alternatively, ahydrogen-containing precursor may be remotely or locally excited in aplasma to treat the interior chamber walls in embodiments. Regions ofexposed silicon may then be etched with more reproducible etch ratesfrom wafer-to-wafer. The silicon etch may be performed using plasmaeffluents formed from a remotely excited fluorine-containing precursor.

Embodiments of the invention include methods of conditioning a substrateprocessing region. The methods include exciting a conditioningfluorine-containing precursor in a conditioning plasma to produceconditioning plasma effluents. The methods further include exposinginterior processing chamber walls to the conditioning plasma effluents.The interior processing chamber walls border a substrate processingregion.

Embodiments of the invention include methods of conditioning a substrateprocessing region. The methods include exciting a hydrogen-containingprecursor in a conditioning plasma to produce conditioning plasmaeffluents. The methods further include exposing interior processingchamber walls to the conditioning plasma effluents. The interiorprocessing chamber walls border a substrate processing region.

Additional embodiments and features are set forth in part in thedescription that follows, and in part will become apparent to thoseskilled in the art upon examination of the specification or may belearned by the practice of the disclosed embodiments. The features andadvantages of the disclosed embodiments may be realized and attained bymeans of the instrumentalities, combinations, and methods described inthe specification.

DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the disclosedembodiments may be realized by reference to the remaining portions ofthe specification and the drawings.

FIG. 1 is a flow chart of a preventative maintenance procedure accordingto embodiments.

FIG. 2 is a flow chart of a preventative maintenance procedure accordingto embodiments.

FIG. 3 is a plot of silicon etch rates without a preventativemaintenance procedure and following a preventative maintenance procedureaccording to embodiments.

FIG. 4A shows a substrate processing chamber according to embodiments ofthe invention.

FIG. 4B shows a showerhead of a substrate processing chamber accordingto embodiments of the invention.

FIG. 5 shows a substrate processing system according to embodiments ofthe invention.

In the appended figures, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If only the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

DETAILED DESCRIPTION

Methods of conditioning interior processing chamber walls of an etchchamber are described. A fluorine-containing precursor may be remotelyor locally excited in a plasma to treat the interior chamber wallsperiodically on a preventative maintenance schedule. The treated wallspromote an even etch rate when used to perform gas-phase etching ofsilicon regions following conditioning. Alternatively, ahydrogen-containing precursor may be remotely or locally excited in aplasma to treat the interior chamber walls in embodiments. Regions ofexposed silicon may then be etched with more reproducible etch ratesfrom wafer-to-wafer. The silicon etch may be performed using plasmaeffluents formed from a remotely excited fluorine-containing precursor.

In order to better understand and appreciate the invention, reference isnow made to FIG. 1 which is a preventative maintenance procedure 100according to embodiments. No substrate or a “dummy” substrate may bepresent in the substrate processing region during the first threeoperations of FIG. 1 according to embodiments. Preventative maintenanceprocedure 100 reduces cost by not relying on the presence of a substrateduring the preventative maintenance operations. Nitrogen trifluoride isflowed into a remote plasma region and a remote plasma power is applied(operation 110) to form conditioning plasma effluents. The remote plasmaregion is separate from the processing region. The conditioning plasmaeffluents are flowed into the substrate processing region (operation120). Other sources of fluorine may be used to augment or replace thenitrogen trifluoride. In general, a conditioning fluorine-containingprecursor may be flowed into the remote plasma region and theconditioning fluorine-containing precursor may include one or more ofatomic fluorine, diatomic fluorine, boron trifluoride, chlorinetrifluoride, nitrogen trifluoride, fluorinated hydrocarbons, sulfurhexafluoride and xenon difluoride. The conditioning plasma effluentstreat the interior chamber walls (operation 125) by chemically alteringthe surfaces.

The last three operations of FIG. 1 are optional but help make thebenefits of the first three operations more clear. A substrate havingexposed regions of silicon is then delivered into the substrateprocessing region (operation 130). The substrate may be a patternedsubstrate and may have additional exposed regions (e.g. of siliconoxide) in embodiments. A flow of nitrogen trifluoride is introduced intothe remote plasma region. Other sources of fluorine may be used toaugment or replace the nitrogen trifluoride. In general, an etchingfluorine-containing precursor may be flowed into the remote plasmaregion and the etching fluorine-containing precursor may include one ormore of atomic fluorine, diatomic fluorine, boron trifluoride, chlorinetrifluoride, nitrogen trifluoride, hydrogen fluoride, perfluorinatedhydrocarbons, sulfur hexafluoride and xenon difluoride. Nitrogentrifluoride offers a particular benefit since it forms long-livedradical-fluorine in the conditioning plasma effluents and the etchingplasma effluents discussed shortly. Radical-fluorine formed fromnitrogen trifluoride remains highly reactive even after passing throughshowerheads and/or ion suppression elements described herein.

The remote plasma region may located within a distinct module separatefrom the processing chamber or a compartment within the processingchamber. The separate plasma region may is fluidly coupled to thesubstrate processing region by through-holes in a showerhead disposedbetween the two regions. The hardware just described (and elaborated onin the equipment section) may also be used in all processes discussedherein.

The etching plasma effluents formed in the remote plasma region are thenflowed into the substrate processing region through the through-holesthe showerhead separating the remote plasma region and the substrateprocessing region. Silicon on the substrate is selectively etched(operation 135) such that silicon may be removed more rapidly than avariety of other materials. The etch selectivity (silicon:silicon oxideor silicon:silicon nitride) may also be greater than or about 70:1,greater than or about 100:1, greater than or about 150:1, greater thanor about 200:1, greater than or about 250:1 or greater than or about300:1 according to embodiments. Regions of exposed tungsten or titaniumnitride may be present, in embodiments, on the patterned substrate andmay be referred to as exposed metallic regions. The etch selectivity(silicon:exposed metallic region) may be greater than or about 100:1,greater than or about 150:1, greater than or about 200:1, greater thanor about 250:1, greater than or about 500:1, greater than or about1000:1, greater than or about 2000:1 or greater than or about 3000:1according to embodiments. The reactive chemical species and any processeffluents are removed from the substrate processing region and then thesubstrate is removed from the substrate processing region (operation145).

The conditioning of the interior processing chamber walls of borderingthe substrate processing region enables the selective etch rate toremain more uniform from wafer to wafer for an extended period of time.The improvement suggests that the chemical termination on the interiorprocessing chamber walls is more stable rather than evolving over time.A qualitative description of the etch rate in comparison to thatattained using unconditioned walls will be described along with FIG. 3.

The flow rate ranges now given for conditioning and etchingfluorine-containing precursors apply to each of flowing operation 110and selective etching operation 135 (as well as all etching operationsdescribed herein). In embodiments, the fluorine-containing precursor(e.g. NF₃) is supplied at a flow rate of between about 5 sccm and about500 sccm, between about 10 sccm and about 300 sccm, between about 25sccm and about 200 sccm, between about 50 sccm and about 150 sccm orbetween about 75 sccm and about 125 sccm. The substrate processingregion and the remote plasma region may be devoid of or essentiallydevoid of hydrogen during treatment operation 125 in embodiments.Similarly, the substrate processing region and the remote plasma regionmay be devoid of or essentially devoid of hydrogen during selectiveetching operation 135 according to embodiments. Alternatively, a veryhigh hydrogen:fluorine atomic flow ratio (e.g. H:F greater than ten) maybe used during selective etching operation 135 (and other etchingoperations described herein) to selectively etch silicon relative to abroader array of materials.

The method also includes applying energy to the conditioning and etchingfluorine-containing precursor in the remote plasma region to generatethe conditioning and etching plasma effluents in each of remote plasmaoperation 110 and selective etching operation 135 (as well as all remoteplasmas described herein). The plasma may be generated using knowntechniques (e.g., radio frequency excitations, capacitively-coupledpower, inductively coupled power). In an embodiment, the energy may beapplied using a capacitively-coupled plasma unit. The remote plasmasource power may be between about 100 watts and about 3000 watts,between about 200 watts and about 2000 watts, between about 300 wattsand about 1000 watts in embodiments. Treatment operation 125 (and alltreatment operations described herein) may also involve a local plasmaexcitation instead of or in addition to the remote plasma excitationaccording to embodiments. The plasma powers of local plasmas used toperform treatment operations herein may involve application of the sameplasma powers as the remote plasmas in embodiments. Local plasmas mayalternatively be referred to herein as “direct” plasmas. When a localplasma is used to replace operations 110-120, the substrate processingregion may be devoid of or essentially devoid of hydrogen inembodiments. Plasmas may be referred to as “conditioning plasmas” duringapplication of the treatment plasma (operation 110) or may be referredto as “etching plasmas” or “remote etching plasmas” during selectiveetching operation 135. Conditioning plasmas may be referred to as“remote conditioning plasmas” or “local conditioning plasmas” todescribe where the plasma is located.

Reference is now made to FIG. 2 which is a preventative maintenanceprocedure 200 according to embodiments. The various traits and processparameters discussed with reference to FIG. 1 may not be repeated hereexcept when they deviate from those traits and process parameters. Nosubstrate or a “dummy” substrate may be present in the substrateprocessing region during the first three operations of FIG. 2 accordingto embodiments. Preventative maintenance procedure 200 reduces cost bynot relying on the presence of a substrate during the preventativemaintenance operations. Ammonia is flowed into a substrate processingregion (operation 210) and a local plasma power is applied (operation220) to treat the interior processing chamber walls bordering thesubstrate processing region (operation 225). Despite the local nature ofthe plasma, the plasma effluents impact and treat the interior chamberwalls (operation 225) by chemically altering the surfaces. The substrateprocessing region may be devoid of or essentially devoid of fluorineduring treatment operation 225 according to embodiments. In general ahydrogen-containing precursor or a nitrogen-and-hydrogen-containingprecursor (which may consist of nitrogen and hydrogen) may be flowedinto the substrate processing region in operation 210. Anitrogen-and-hydrogen-containing precursor may include one or both ofammonia and hydrazine according to embodiments, and may be devoid offluorine according to embodiments.

The last three optional operations of FIG. 2 are again included toimprove understanding of the impact of treatment operation 225. Asubstrate having exposed regions of silicon is then delivered into thesubstrate processing region (operation 230). The substrate may be apatterned substrate and may have additional exposed regions (e.g. ofsilicon oxide) in embodiments. A flow of nitrogen trifluoride isintroduced into a remote plasma region. Other sources of fluorine may beused to augment or replace the nitrogen trifluoride. In general, afluorine-containing precursor may be flowed into the remote plasmaregion and the fluorine-containing precursor may include one or more ofatomic fluorine, diatomic fluorine, boron trifluoride, chlorinetrifluoride, nitrogen trifluoride, hydrogen fluoride, fluorinatedhydrocarbons, sulfur hexafluoride and xenon difluoride. As before,nitrogen trifluoride is used in a preferred embodiment owing to theformation of long-lived radical-fluorine in the plasma effluents. Thefluorine-containing precursor may be devoid of hydrogen according toembodiments.

The remote plasma region herein may be within a distinct module from theprocessing chamber or a compartment within the processing chamberaccording to embodiments. The separate plasma region may is fluidlycoupled to the substrate processing region by through-holes in ashowerhead disposed between the two regions. The plasma effluents formedin the remote plasma region are then flowed into the substrateprocessing region through the through-holes the showerhead. Silicon onthe substrate is selectively etched (operation 235) such that siliconmay be removed more rapidly than a variety of other materials. Theremote plasma region and the substrate processing region may be devoidof hydrogen during selective etching operation 235 according toembodiments. The etch selectivity described earlier apply to selectiveetching operation 235 as well. The reactive chemical species and anyprocess effluents are removed from the substrate processing region andthen the substrate is removed from the substrate processing region(operation 245).

The conditioning of the interior processing chamber walls inpreventative maintenance procedure 200 may result in a chemicallydistinct layer formed on the interior surfaces bordering the substrateprocessing region when compared with preventative maintenance procedure100. The etch rate, however, may be more similar from wafer to waferrelative to etch rates obtained using untreated chamber walls borderingthe substrate processing region. The treated chamber walls enable theetch rate to remain more uniform from wafer to wafer for an extendedperiod of time (e.g. days). The improvement suggests that the chemicaltermination on the interior processing chamber walls, though distinctfrom the treatment of FIG. 1, is still more stable rather than evolvingover time (e.g. from one substrate to a subsequently processedsubstrate).

Flow rates for the fluorine-containing precursor were given earlier andare not repeated here. The flow rate ranges for the hydrogen-containingprecursor in treatment operation 225 are now described since nohydrogen-containing precursor was present in preventative maintenanceprocedure 100. The hydrogen-containing precursor (e.g. NH₃) is suppliedat a flow rate of between about 5 sccm and about 500 sccm, between about10 sccm and about 300 sccm, between about 25 sccm and about 200 sccm,between about 50 sccm and about 150 sccm or between about 75 sccm andabout 125 sccm according to embodiments.

The method also includes applying energy to the hydrogen-containingprecursor in the substrate processing region to generate the plasmaeffluents which treat the interior chamber walls bordering the substrateprocessing region in treatment operation 125. The plasma may begenerated using known techniques (e.g., radio frequency excitations,capacitively-coupled power, inductively coupled power). In anembodiment, the energy may be applied using a capacitively-coupledplasma unit. The local plasma power may be between about 100 watts andabout 3000 watts, between about 200 watts and about 2000 watts, betweenabout 300 watts and about 1000 watts in embodiments. Treatment operation125 (and all treatment operations described herein) may also involve aremote plasma excitation instead of or in addition to the local plasmaexcitation according to embodiments. The plasma powers of remote plasmasused to perform treatment operations herein may involve application ofthe same plasma powers as the local plasmas in embodiments. When aremote plasma is used, the substrate processing region and the remoteplasma region may be devoid of or essentially devoid of fluorineaccording to embodiments.

In all embodiments described herein which use a remote plasma, the term“plasma-free” may be used to describe the substrate processing regionduring application of no or essentially no plasma power. A plasma-freesubstrate processing region may be used for both treatment operations(operations 125 and 225) and selective etching operations (operations135 and 235) in embodiments.

The temperature of the substrate for all embodiments described hereinmay be greater than 0° C. during the etch process. The substratetemperature may be greater than or about 20° C. and less than or about300° C. At the high end of this substrate temperature range, the siliconetch rate drops. At the lower end of this substrate temperature range,silicon oxide and silicon nitride begin to etch and so the selectivitydrops. In disclosed embodiments, the temperature of the substrate duringthe etches described herein may be greater than or about 30° C. whileless than or about 200° C. or greater than or about 40° C. while lessthan or about 150° C. The substrate temperature may be below 100° C.,below or about 80° C., below or about 65° C. or below or about 50° C. indisclosed embodiments.

The data further show an increase in silicon etch rate as a function ofprocess pressure during selective etching operations 135 and 235. Thisis suspected to result from a higher probability of combining two ormore fluorine-containing effluents. The etch process then begins toremove silicon oxide, silicon nitride and other materials. The pressurewithin the substrate processing region may be below or about 10 Torr,below or about 5 Torr, below or about 3 Torr, below or about 2 Torr,below or about 1 Torr or below or about 750 mTorr according toembodiments. In order to ensure adequate etch rate, the pressure may beabove or about 0.05 Torr, above or about 0.1 Torr, above or about 0.2Torr or above or about 0.4 Torr in embodiments. Any of the upper limitson pressure may be combined with lower limits according to embodiments.

A pre-treatment may be used, in embodiments, to remove a thin oxidelayer on the surfaces of the exposed silicon regions. The pre-treatmentoccurs before selectively etching the silicon (operations 135 or 235).Thin oxide layers often form when exposing silicon to oxygen in one formor another (e.g. atmospheric conditions). The thin oxide layer can makethe silicon regions behave more like silicon oxide regions, in part,because the selectivities of the processes reported herein are so high.The thin silicon oxide layer is often referred to as a “native” oxideand may be removed using a variety of processes known to those of skillin the art. For example, a Siconi™ etch may be used to remove the nativeoxide. In other words, a fluorine-containing precursor and ahydrogen-containing precursor may be combined in a remote plasma regionand excited in a plasma. The atomic flow ratio H:F during thepre-treatment Siconi™ may be between about 0.5:1 and about 8:1 to ensurethe production of solid by-products on the exposed silicon surfaces. Thenative oxide is consumed during the production of these solidby-products in embodiments of the invention. The temperature of thepatterned substrate during the Siconi™ etch may be below the sublimationtemperature of the solid by-products. The temperature of the patternedsubstrate may be raised above the sublimation temperature afterformation of the solid by-products to remove the solid by-products. Thesublimation completes the removal of the native oxide from the exposedsilicon.

Alternatively, the native oxide can be removed by a hydrogen plasmaformed in the substrate processing region. The local pre-treatmentplasma is created by applying a local plasma power above or about 200watts and below or about 3000 watts or above or about 300 watts andbelow or about 2000 watts in embodiments. Regardless of the method used,the native oxide (if present) is removed before the operation of etchingthe exposed silicon. Techniques for removing the native oxide may becarried out in the same substrate processing region used to selectivelyetch the silicon, or each of these processes may be performed inseparate chambers. However, the patterned substrate should not beexposed to moisture or an atmospheric environment during the transferbetween separate chambers. It should also be noted that the terms“exposed silicon region” and “exposed silicon” will be used hereinregardless of whether a native oxide is present.

An advantage of the processes described herein lies in the conformalrate of removal of metal-containing material from the substrate. Themethods do not rely on a bias power to accelerate etchants towards thesubstrate, which reduces the tendency of the etch processes to removematerial on the tops and bottom of trenches before material on thesidewalls can be removed. As used herein, a conformal etch processrefers to a generally uniform removal rate of material from a patternedsurface regardless of the shape of the surface. The surface of the layerbefore and after the etch process are generally parallel. A personhaving ordinary skill in the art will recognize that the etch processlikely cannot be 100% conformal and thus the term “generally” allows foracceptable tolerances.

In each remote plasma or local plasma described herein, the flows of theprecursors into the remote plasma region may further include one or morerelatively inert gases such as He, N₂, Ar. The inert gas can be used toimprove plasma stability, ease plasma initiation, and improve processuniformity. Argon is helpful, as an additive, to promote the formationof a stable plasma. Process uniformity is generally increased whenhelium is included. These additives are present in embodimentsthroughout this specification. Flow rates and ratios of the differentgases may be used to control etch rates and etch selectivity.

In embodiments, an ion suppressor as described in the exemplaryequipment section may be used to provide radical and/or neutral speciesfor selectively etching substrates. The ion suppressor may also bereferred to as an ion suppression element. In embodiments, for example,the ion suppressor is used to filter fluorine-containing plasmaeffluents to selectively etch silicon. The ion suppressor may beincluded in each exemplary process described herein. Using the plasmaeffluents, an etch rate selectivity of metal-containing material to awide variety of materials may be achieved.

The ion suppressor may be used to provide a reactive gas having a higherconcentration of radicals than ions. The ion suppressor functions todramatically reduce or substantially eliminate ionically charged speciestraveling from the plasma generation region to the substrate. Theelectron temperature may be measured using a Langmuir probe in thesubstrate processing region during excitation of a plasma in the remoteplasma region on the other side of the ion suppressor. In embodiments,the electron temperature may be less than 0.5 eV, less than 0.45 eV,less than 0.4 eV, or less than 0.35 eV. These extremely low values forthe electron temperature are enabled by the presence of the showerheadand/or the ion suppressor positioned between the substrate processingregion and the remote plasma region. Uncharged neutral and radicalspecies may pass through the openings in the ion suppressor to react atthe substrate. Because most of the charged particles of a plasma arefiltered or removed by the ion suppressor, the substrate is notnecessarily biased during the etch process. Such a process usingradicals and other neutral species can reduce plasma damage compared toconventional plasma etch processes that include sputtering andbombardment. The ion suppressor helps control the concentration of ionicspecies in the reaction region at a level that assists the process.Embodiments of the present invention are also advantageous overconventional wet etch processes where surface tension of liquids cancause bending and peeling of small features.

FIG. 3 is a plot of silicon etch rates 300 without a preventativemaintenance procedure and following a preventative maintenance procedureaccording to embodiments. The plot of silicon etch rates 300 includesetch rate measurements performed over a sequence of 900 wafers (anexample of substrates). Data 310 are included showing changes to etchrate of silicon over time while processing a sequence of wafers withoutany treatment operation prior to processing the wafers. The etch ratecan be shown drifting upward as, presumably, the interior surfacesbordering the substrate processing region evolve over time. Data 320 arealso included which show a relatively stable silicon etch rate followingtreatment operation 125 (using a fluorine-containing precursor). Data330 are also included which show a relatively silicon etch ratefollowing treatment 225 (using a hydrogen-containing precursor). Thedata following fluorine treatment operation 125 and the data followinghydrogen treatment operation 225 are both indicative of a stable siliconetch rate which are each desirable in a manufacturing environment. Notethat the magnitude of the etch rate following each of the twopreventative maintenance operations differ from one another, presumablybecause the surfaces are covered with different chemical species. Theinterior surfaces bordering the substrate processing region are coatedafter fluorine treatment operation 125 such that the etch rate is stableat a value similar to the first wafer processed in an untreated chamber(the left-most data point in untreated data 310). The interior surfacesare coated after hydrogen treatment operation 225 such that the etchrate is stable at a higher silicon etch rate which roughly matches theasymptotic extension of the etch rates for untreated data 310 after alarge number of wafers is processed. The appropriate preventativemaintenance procedure may be selected based on a variety of processcharacteristics such as magnitude of etch rate, particle performance andetch rate within-wafer uniformity.

Additional process parameters are disclosed in the course of describingan exemplary processing chamber and system.

Exemplary Processing System

Processing chambers that may implement embodiments of the presentinvention may be included within processing platforms such as theCENTURA® and PRODUCER® systems, available from Applied Materials, Inc.of Santa Clara, Calif.

FIG. 4A is a substrate processing chamber 1001 according to embodiments.A remote plasma system 1010 may process a fluorine-containing precursorand/or a hydrogen-containing precursor which then travels through a gasinlet assembly 1011. Two distinct gas supply channels are visible withinthe gas inlet assembly 1011. A first channel 1012 carries a gas thatpasses through the remote plasma system 1010 (RPS), while a secondchannel 1013 bypasses the remote plasma system 1010. Either channel maybe used for the fluorine-containing precursor, in embodiments. On theother hand, the first channel 1012 may be used for the process gas andthe second channel 1013 may be used for a treatment gas. The lid (orconductive top portion) 1021 and a perforated partition 1053 are shownwith an insulating ring 1024 in between, which allows an AC potential tobe applied to the lid 1021 relative to perforated partition 1053. The ACpotential strikes a plasma in chamber plasma region 1020. The processgas may travel through first channel 1012 into chamber plasma region1020 and may be excited by a plasma in chamber plasma region 1020 aloneor in combination with remote plasma system 1010. If the process gas(the fluorine-containing precursor) flows through second channel 1013,then only the chamber plasma region 1020 is used for excitation. Thecombination of chamber plasma region 1020 and/or remote plasma system1010 may be referred to as a remote plasma region herein. The perforatedpartition (also referred to as a showerhead) 1053 separates chamberplasma region 1020 from a substrate processing region 1070 beneathshowerhead 1053. Showerhead 1053 allows a plasma present in chamberplasma region 1020 to avoid directly exciting gases in substrateprocessing region 1070, while still allowing excited species to travelfrom chamber plasma region 1020 into substrate processing region 1070.

Showerhead 1053 is positioned between chamber plasma region 1020 andsubstrate processing region 1070 and allows plasma effluents (excitedderivatives of precursors or other gases) created within remote plasmasystem 1010 and/or chamber plasma region 1020 to pass through aplurality of through-holes 1056 that traverse the thickness of theplate. The showerhead 1053 also has one or more hollow volumes 1051which can be filled with a precursor in the form of a vapor or gas (suchas a fluorine-containing precursor) and pass through blind-holes 1055into substrate processing region 1070 but not directly into chamberplasma region 1020. Showerhead 1053 is thicker than the length of thesmallest diameter 1050 of the through-holes 1056 in embodiments. Tomaintain a significant concentration of excited species penetrating fromchamber plasma region 1020 to substrate processing region 1070, thelength 1026 of the smallest diameter 1050 of the through-holes may berestricted by forming larger diameter portions of through-holes 1056part way through the showerhead 1053. The length of the smallestdiameter 1050 of the through-holes 1056 may be the same order ofmagnitude as the smallest diameter of the through-holes 1056 or less inembodiments. Showerhead 1053 may be referred to as a dual-channelshowerhead, a dual-zone showerhead, a multi-channel showerhead or amulti-zone showerhead to convey the existence of through-holes andblind-holes for introducing precursors.

Showerhead 1053 may be configured to serve the purpose of an ionsuppressor as shown in FIG. 4A. Alternatively, a separate processingchamber element may be included (not shown) which suppresses the ionconcentration traveling into substrate processing region 1070. Lid 1021and showerhead 1053 may function as a first electrode and secondelectrode, respectively, so that lid 1021 and showerhead 1053 mayreceive different electric voltages. In these configurations, electricalpower (e.g., RF power) may be applied to lid 1021, showerhead 1053, orboth. For example, electrical power may be applied to lid 1021 whileshowerhead 1053 (serving as ion suppressor) is grounded. The substrateprocessing system may include a RF generator that provides electricalpower to the lid and/or showerhead 1053. The voltage applied to lid 1021may facilitate a uniform distribution of plasma (i.e., reduce localizedplasma) within chamber plasma region 1020. To enable the formation of aplasma in chamber plasma region 1020, insulating ring 1024 mayelectrically insulate lid 1021 from showerhead 1053. Insulating ring1024 may be made from a ceramic and may have a high breakdown voltage toavoid sparking. Portions of substrate processing chamber 1001 near thecapacitively-coupled plasma components just described may furtherinclude a cooling unit (not shown) that includes one or more coolingfluid channels to cool surfaces exposed to the plasma with a circulatingcoolant (e.g., water).

In the embodiment shown, showerhead 1053 may distribute (viathrough-holes 1056) process gases which contain fluorine, hydrogenand/or plasma effluents of such process gases upon excitation by aplasma in chamber plasma region 1020. In embodiments, the process gasintroduced into the remote plasma system 1010 and/or chamber plasmaregion 1020 may contain fluorine. The process gas may also include acarrier gas such as helium, argon, nitrogen (N₂), etc. Plasma effluentsmay include ionized or neutral derivatives of the process gas and mayalso be referred to herein as radical-fluorine and/or radical-hydrogenreferring to the atomic constituent of the process gas introduced.

Through-holes 1056 are configured to suppress the migration ofionically-charged species out of the chamber plasma region 1020 whileallowing uncharged neutral or radical species to pass through showerhead1053 into substrate processing region 1070. These uncharged species mayinclude highly reactive species that are transported with less-reactivecarrier gas by through-holes 1056. As noted above, the migration ofionic species by through-holes 1056 may be reduced, and in someinstances completely suppressed. Controlling the amount of ionic speciespassing through showerhead 1053 provides increased control over the gasmixture brought into contact with the underlying wafer substrate, whichin turn increases control of the deposition and/or etch characteristicsof the gas mixture. For example, adjustments in the ion concentration ofthe gas mixture can alter the etch selectivity (e.g., thesilicon:silicon nitride etch rate ratio).

In embodiments, the number of through-holes 1056 may be between about 60and about 2000. Through-holes 1056 may have a variety of shapes but aremost easily made round. The smallest diameter 1050 of through-holes 1056may be between about 0.5 mm and about 20 mm or between about 1 mm andabout 6 mm in embodiments. There is also latitude in choosing thecross-sectional shape of through-holes, which may be made conical,cylindrical or combinations of the two shapes. The number of blind-holes1055 used to introduce unexcited precursors into substrate processingregion 1070 may be between about 100 and about 5000 or between about 500and about 2000 in different embodiments. The diameter of the blind-holes1055 may be between about 0.1 mm and about 2 mm.

Through-holes 1056 may be configured to control the passage of theplasma-activated gas (i.e., the ionic, radical, and/or neutral species)through showerhead 1053. For example, the aspect ratio of the holes(i.e., the hole diameter to length) and/or the geometry of the holes maybe controlled so that the flow of ionically-charged species in theactivated gas passing through showerhead 1053 is reduced. Through-holes1056 in showerhead 1053 may include a tapered portion that faces chamberplasma region 1020, and a cylindrical portion that faces substrateprocessing region 1070. The cylindrical portion may be proportioned anddimensioned to control the flow of ionic species passing into substrateprocessing region 1070. An adjustable electrical bias may also beapplied to showerhead 1053 as an additional means to control the flow ofionic species through showerhead 1053.

Alternatively, through-holes 1056 may have a smaller inner diameter (ID)toward the top surface of showerhead 1053 and a larger ID toward thebottom surface. In addition, the bottom edge of through-holes 1056 maybe chamfered to help evenly distribute the plasma effluents in substrateprocessing region 1070 as the plasma effluents exit the showerhead andpromote even distribution of the plasma effluents and precursor gases.The smaller ID may be placed at a variety of locations alongthrough-holes 1056 and still allow showerhead 1053 to reduce the iondensity within substrate processing region 1070. The reduction in iondensity results from an increase in the number of collisions with wallsprior to entry into substrate processing region 1070. Each collisionincreases the probability that an ion is neutralized by the acquisitionor loss of an electron from the wall. Generally speaking, the smaller IDof through-holes 1056 may be between about 0.2 mm and about 20 mm. Inother embodiments, the smaller ID may be between about 1 mm and 6 mm orbetween about 0.2 mm and about 5 mm. Further, aspect ratios of thethrough-holes 1056 (i.e., the smaller ID to hole length) may beapproximately 1 to 20. The smaller ID of the through-holes may be theminimum ID found along the length of the through-holes. The crosssectional shape of through-holes 1056 may be generally cylindrical,conical, or any combination thereof.

FIG. 4B is a bottom view of a showerhead 1053 for use with a processingchamber according to embodiments. Showerhead 1053 corresponds with theshowerhead shown in FIG. 4A. Through-holes 1056 are depicted with alarger inner-diameter (ID) on the bottom of showerhead 1053 and asmaller ID at the top. Blind-holes 1055 are distributed substantiallyevenly over the surface of the showerhead, even amongst thethrough-holes 1056 which helps to provide more even mixing than otherembodiments described herein.

An exemplary patterned substrate may be supported by a pedestal (notshown) within substrate processing region 1070 when fluorine-containingplasma effluents or hydrogen-containing plasma effluents arrive throughthrough-holes 1056 in showerhead 1053. Though substrate processingregion 1070 may be equipped to support a plasma for other processes suchas curing, no plasma is present during the etching of patternedsubstrate, in embodiments.

A plasma may be ignited either in chamber plasma region 1020 aboveshowerhead 1053 or substrate processing region 1070 below showerhead1053. A plasma is present in chamber plasma region 1020 to produce theradical-fluorine from an inflow of the fluorine-containing precursor. AnAC voltage typically in the radio frequency (RF) range is appliedbetween the conductive top portion (lid 1021) of the processing chamberand showerhead 1053 to ignite a plasma in chamber plasma region 1020during deposition. An RF power supply generates a high RF frequency of13.56 MHz but may also generate other frequencies alone or incombination with the 13.56 MHz frequency.

The top plasma may be left at low or no power when the bottom plasma inthe substrate processing region 1070 is turned on to either cure a filmor clean the interior surfaces bordering substrate processing region1070. A plasma in substrate processing region 1070 is ignited byapplying an AC voltage between showerhead 1053 and the pedestal orbottom of the chamber. A cleaning gas may be introduced into substrateprocessing region 1070 while the plasma is present.

The pedestal may have a heat exchange channel through which a heatexchange fluid flows to control the temperature of the substrate. Thisconfiguration allows the substrate temperature to be cooled or heated tomaintain relatively low temperatures (from room temperature throughabout 120° C.). The heat exchange fluid may comprise ethylene glycol andwater. The wafer support platter of the pedestal (preferably aluminum,ceramic, or a combination thereof) may also be resistively heated toachieve relatively high temperatures (from about 120° C. through about1100° C.) using an embedded single-loop embedded heater elementconfigured to make two full turns in the form of parallel concentriccircles. An outer portion of the heater element may run adjacent to aperimeter of the support platter, while an inner portion runs on thepath of a concentric circle having a smaller radius. The wiring to theheater element passes through the stem of the pedestal.

The chamber plasma region and/or a region in a remote plasma system maybe referred to as a remote plasma region. In embodiments, the radicalprecursors (e.g. radical-fluorine and/or radical-hydrogen) are formed inthe remote plasma region and travel into the substrate processing regionwhere they may individually react with chamber walls or the substratesurface. Plasma power may essentially be applied only to the remoteplasma region, in embodiments, to ensure that the radical-fluorine orthe radical-hydrogen (which may also be referred to as plasma effluents)are not further excited in the substrate processing region.

In embodiments employing a chamber plasma region, the excited plasmaeffluents are generated in a section of the substrate processing regionpartitioned from a deposition region. The deposition region, also knownherein as the substrate processing region, is where the plasma effluentsmix and react to etch the patterned substrate (e.g., a semiconductorwafer). The excited plasma effluents may also be accompanied by inertgases (in the exemplary case, argon). The substrate processing regionmay be described herein as “plasma-free” during etching of thesubstrate. “Plasma-free” does not necessarily mean the region is devoidof plasma. A relatively low concentration of ionized species and freeelectrons created within the remote plasma region do travel throughpores (apertures) in the partition (showerhead/ion suppressor) due tothe shapes and sizes of through-holes 1056. In some embodiments, thereis essentially no concentration of ionized species and free electronswithin the substrate processing region. In embodiments, the electrontemperature may be less than 0.5 eV, less than 0.45 eV, less than 0.4eV, or less than 0.35 eV in substrate processing region 1070 duringexcitation of a remote plasma. The borders of the plasma in the chamberplasma region are hard to define and may encroach upon the substrateprocessing region through the apertures in the showerhead. In the caseof an inductively-coupled plasma, a small amount of ionization may beeffected within the substrate processing region directly. Furthermore, alow intensity plasma may be created in the substrate processing regionwithout eliminating desirable features of the forming film. All causesfor a plasma having much lower intensity ion density than the chamberplasma region (or a remote plasma region, for that matter) during thecreation of the excited plasma effluents do not deviate from the scopeof “plasma-free” as used herein.

The fluorine-containing precursor) may be flowed into chamber plasmaregion 1020 at rates between about 5 sccm and about 500 sccm, betweenabout 10 sccm and about 300 sccm, between about 25 sccm and about 200sccm, between about 50 sccm and about 150 sccm or between about 75 sccmand about 125 sccm in embodiments.

The flow rate of the fluorine-containing precursor into the chamber mayaccount for 0.05% to about 20% by volume of the overall gas mixture; theremainder being carrier gases. The fluorine-containing precursor areflowed into the remote plasma region but the plasma effluents have thesame volumetric flow ratio, in embodiments. A purge or carrier gas maybe initiated into the remote plasma region before that of thefluorine-containing gas to stabilize the pressure within the remoteplasma region.

Plasma power applied to the remote plasma region can be a variety offrequencies or a combination of multiple frequencies. In the exemplaryprocessing system the plasma is provided by RF power delivered betweenlid 1021 and showerhead 1053. In an embodiment, the energy is appliedusing a capacitively-coupled plasma unit. When using a Frontier™ orsimilar system, the remote plasma source power may be between about 100watts and about 3000 watts, between about 200 watts and about 2500watts, between about 300 watts and about 2000 watts, or between about500 watts and about 1500 watts in embodiments. The RF frequency appliedin the exemplary processing system may be low RF frequencies less thanabout 200 kHz, high RF frequencies between about 10 MHz and about 15 MHzor microwave frequencies greater than or about 1 GHz in embodiments.

Substrate processing region 1070 can be maintained at a variety ofpressures during the flow of carrier gases and plasma effluents intosubstrate processing region 1070. The pressure within the substrateprocessing region is below or about 50 Torr, below or about 30 Torr,below or about 20 Torr, below or about 10 Torr or below or about 5 Torr.The pressure may be above or about 0.1 Torr, above or about 0.2 Torr,above or about 0.5 Torr or above or about 1 Torr in embodiments. Lowerlimits on the pressure may be combined with upper limits on the pressureto obtain embodiments.

In one or more embodiments, the substrate processing chamber 1001 can beintegrated into a variety of multi-processing platforms, including theProducer™ GT, Centura™ AP and Endura™ platforms available from AppliedMaterials, Inc. located in Santa Clara, Calif. Such a processingplatform is capable of performing several processing operations withoutbreaking vacuum. Processing chambers that may implement embodiments ofthe present invention may include dielectric etch chambers or a varietyof chemical vapor deposition chambers, among other types of chambers.

Embodiments of the etching systems may be incorporated into largerfabrication systems for producing integrated circuit chips. FIG. 5 showsone such system 1101 of etching, deposition, baking and curing chambersaccording to embodiments. In the figure, a pair of FOUPs (front openingunified pods) 1102 supply substrate substrates (e.g., 300 mm diameterwafers) that are received by robotic arms 1104 and placed into a lowpressure holding areas 1106 before being placed into one of the waferprocessing chambers 1108 a-f. A second robotic arm 1110 may be used totransport the substrate wafers from the low pressure holding areas 1106to the wafer processing chambers 1108 a-f and back. Each waferprocessing chamber 1108 a-f, can be outfitted to perform a number ofsubstrate processing operations including the dry etch processesdescribed herein in addition to cyclical layer deposition (CLD), atomiclayer deposition (ALD), chemical vapor deposition (CVD), physical vapordeposition (PVD), etch, pre-clean, degas, orientation and othersubstrate processes.

The wafer processing chambers 1108 a-f may include one or more systemcomponents for depositing, annealing, curing and/or etching a dielectricfilm on the substrate wafer. In one configuration, two pairs of theprocessing chamber (e.g., 1108 c-d and 1108 e-f) may be used to depositdielectric material on the substrate, and the third pair of processingchambers (e.g., 1108 a-b) may be used to etch the deposited dielectric.In another configuration, all three pairs of chambers (e.g., 1108 a-f)may be configured to etch a dielectric film on the substrate. Any one ormore of the processes described may be carried out on chamber(s)separated from the fabrication system shown in different embodiments.

The substrate processing system is controlled by a system controller. Inan exemplary embodiment, the system controller includes a hard diskdrive, a floppy disk drive and a processor. The processor contains asingle-board computer (SBC), analog and digital input/output boards,interface boards and stepper motor controller boards. Various parts ofCVD system conform to the Versa Modular European (VME) standard whichdefines board, card cage, and connector dimensions and types. The VMEstandard also defines the bus structure as having a 16-bit data bus anda 24-bit address bus.

System controller 1157 is used to control motors, valves, flowcontrollers, power supplies and other functions required to carry outprocess recipes described herein. A gas handling system 1155 may also becontrolled by system controller 1157 to introduce gases to one or all ofthe wafer processing chambers 1108 a-f. System controller 1157 may relyon feedback from optical sensors to determine and adjust the position ofmovable mechanical assemblies in gas handling system 1155 and/or inwafer processing chambers 1108 a-f. Mechanical assemblies may includethe robot, throttle valves and susceptors which are moved by motorsunder the control of system controller 1157.

In an exemplary embodiment, system controller 1157 includes a hard diskdrive (memory), USB ports, a floppy disk drive and a processor. Systemcontroller 1157 includes analog and digital input/output boards,interface boards and stepper motor controller boards. Various parts ofmulti-chamber processing system 1101 which contains substrate processingchamber 1001 are controlled by system controller 1157. The systemcontroller executes system control software in the form of a computerprogram stored on computer-readable medium such as a hard disk, a floppydisk or a flash memory thumb drive. Other types of memory can also beused. The computer program includes sets of instructions that dictatethe timing, mixture of gases, chamber pressure, chamber temperature, RFpower levels, susceptor position, and other parameters of a particularprocess.

A process for etching, depositing or otherwise processing a film on asubstrate or a process for cleaning chamber can be implemented using acomputer program product that is executed by the controller. Thecomputer program code can be written in any conventional computerreadable programming language: for example, 68000 assembly language, C,C++, Pascal, Fortran or others. Suitable program code is entered into asingle file, or multiple files, using a conventional text editor, andstored or embodied in a computer usable medium, such as a memory systemof the computer. If the entered code text is in a high level language,the code is compiled, and the resultant compiler code is then linkedwith an object code of precompiled Microsoft Windows® library routines.To execute the linked, compiled object code the system user invokes theobject code, causing the computer system to load the code in memory. TheCPU then reads and executes the code to perform the tasks identified inthe program.

The interface between a user and the controller may be via atouch-sensitive monitor and may also include a mouse and keyboard. Inone embodiment two monitors are used, one mounted in the clean room wallfor the operators and the other behind the wall for the servicetechnicians. The two monitors may simultaneously display the sameinformation, in which case only one is configured to accept input at atime. To select a particular screen or function, the operator touches adesignated area on the display screen with a finger or the mouse. Thetouched area changes its highlighted color, or a new menu or screen isdisplayed, confirming the operator's selection.

As used herein “substrate” may be a support substrate with or withoutlayers formed thereon. The patterned substrate may be an insulator or asemiconductor of a variety of doping concentrations and profiles andmay, for example, be a semiconductor substrate of the type used in themanufacture of integrated circuits. Exposed “silicon” of the patternedsubstrate is predominantly Si but may include minority concentrations ofother elemental constituents (e.g. nitrogen, oxygen, hydrogen, carbon).Exposed “silicon nitride” of the patterned substrate is predominantlySi₃N₄ but may include minority concentrations of other elementalconstituents (e.g. oxygen, hydrogen, carbon). Exposed “silicon oxide” ofthe patterned substrate is predominantly SiO₂ but may include minorityconcentrations of other elemental constituents (e.g. nitrogen, hydrogen,carbon). In some embodiments, silicon oxide films etched using themethods disclosed herein consist essentially of silicon and oxygen.“Titanium nitride” is predominantly titanium and nitrogen but mayinclude minority concentrations of other elemental constituents (e.g.oxygen, hydrogen, carbon). Titanium nitride may consist essentially oftitanium and nitrogen. “Tungsten oxide” is predominantly tungsten andoxygen but may include minority concentrations of other elementalconstituents (e.g. nitrogen, hydrogen, carbon). Titanium nitride mayconsist essentially of tungsten and oxygen. “Tungsten” is predominantlytungsten but may include minority concentrations of other elementalconstituents (e.g. nitrogen, oxygen, hydrogen, carbon).

The term “precursor” is used to refer to any process gas which takespart in a reaction to either remove material from or deposit materialonto a surface. “Plasma effluents” describe gas exiting from the chamberplasma region and entering the substrate processing region. Plasmaeffluents are in an “excited state” wherein at least some of the gasmolecules are in vibrationally-excited, dissociated and/or ionizedstates. A “radical precursor” is used to describe plasma effluents (agas in an excited state which is exiting a plasma) which participate ina reaction to either remove material from or deposit material on asurface. “Radical-fluorine” (or “radical-hydrogen”) are radicalprecursors which contain fluorine (or hydrogen) but may contain otherelemental constituents. The phrase “inert gas” refers to any gas whichdoes not form chemical bonds when etching or being incorporated into afilm. Exemplary inert gases include noble gases but may include othergases so long as no chemical bonds are formed when (typically) traceamounts are trapped in a film.

The terms “gap” and “trench” are used throughout with no implicationthat the etched geometry has a large horizontal aspect ratio. Viewedfrom above the surface, trenches may appear circular, oval, polygonal,rectangular, or a variety of other shapes. A trench may be in the shapeof a moat around an island of material. The term “via” is used to referto a low aspect ratio trench (as viewed from above) which may or may notbe filled with metal to form a vertical electrical connection. As usedherein, a conformal etch process refers to a generally uniform removalof material on a surface in the same shape as the surface, i.e., thesurface of the etched layer and the pre-etch surface are generallyparallel. A person having ordinary skill in the art will recognize thatthe etched interface likely cannot be 100% conformal and thus the term“generally” allows for acceptable tolerances.

Having disclosed several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of thedisclosed embodiments. Additionally, a number of well known processesand elements have not been described to avoid unnecessarily obscuringthe present invention. Accordingly, the above description should not betaken as limiting the scope of the invention.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimits of that range is also specifically disclosed. Each smaller rangebetween any stated value or intervening value in a stated range and anyother stated or intervening value in that stated range is encompassed.The upper and lower limits of these smaller ranges may independently beincluded or excluded in the range, and each range where either, neitheror both limits are included in the smaller ranges is also encompassedwithin the invention, subject to any specifically excluded limit in thestated range. Where the stated range includes one or both of the limits,ranges excluding either or both of those included limits are alsoincluded.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise. Thus, for example, reference to “a process” includes aplurality of such processes and reference to “the dielectric material”includes reference to one or more dielectric materials and equivalentsthereof known to those skilled in the art, and so forth.

Also, the words “comprise,” “comprising,” “include,” “including,” and“includes” when used in this specification and in the following claimsare intended to specify the presence of stated features, integers,components, or steps, but they do not preclude the presence or additionof one or more other features, integers, components, steps, acts, orgroups.

The invention claimed is:
 1. A method of conditioning a substrateprocessing region, the method comprising: exciting a conditioningfluorine-containing precursor in a conditioning plasma to produceconditioning plasma effluents; exposing interior processing chamberwalls to the conditioning plasma effluents, wherein the interiorprocessing chamber walls border a substrate processing region andexposing interior processing chamber walls to the conditioning plasmaeffluents results in a chemical termination on the interior processingchamber walls; (i) transferring a substrate into the substrateprocessing region following the operation of exposing the interiorprocessing chamber walls to the conditioning plasma effluents, whereinthe substrate comprises exposed silicon region; (ii) flowing an etchingfluorine-containing precursor into a remote plasma region fluidlycoupled to the substrate processing region while forming a remote plasmain the remote plasma region to produce etching plasma effluents; and(iii) etching the exposed silicon region by flowing the etching plasmaeffluents into the substrate processing region through through-holes ina showerhead, wherein the showerhead is disposed between the remoteplasma region and the substrate processing region wherein repeatedsubstrate processing does not cause the chemical termination on theinterior processing chamber walls to evolve over time.
 2. The method ofclaim 1 wherein the conditioning fluorine-containing precursor comprisesone or more of atomic fluorine, diatomic fluorine, boron trifluoride,chlorine trifluoride, nitrogen trifluoride, perfluorinated hydrocarbons,sulfur hexafluoride and xenon difluoride.
 3. The method of claim 1wherein the etching fluorine-containing precursor comprises one or moreof atomic fluorine, diatomic fluorine, boron trifluoride, chlorinetrifluoride, nitrogen trifluoride, hydrogen fluoride, fluorinatedhydrocarbons, sulfur hexafluoride and xenon difluoride.
 4. The method ofclaim 1 wherein the substrate processing region is essentially devoid ofhydrogen during the operation of exposing the interior processingchamber walls to the conditioning plasma effluents.
 5. The method ofclaim 1 wherein the conditioning plasma is a local conditioning plasmainside the substrate processing region.
 6. The method of claim 1 whereinthe conditioning plasma is a remote conditioning plasma outside thesubstrate processing region and the conditioning plasma effluents areflowed from the remote plasma into the substrate processing region. 7.The method of claim 1 wherein the repeated substrate processing exhibitsa stable silicon etch rate over 900 substrates.